Aortic valve disease is the third most common congenital left heart lesion, affecting 8% of all children born with heart defects. Aortic valve replacement (AVR) in children, while feasible, carries a significant early and late morbidity and mortality such that by 10 years following AVR only 47% of children are alive and without valve re-replacement. Complications of anticoagulation, infection and valve dysfunction are some of the causes of morbidity and mortality in active children. For this reason alternative procedures such as aortic valve repair (AVre), remain a preferable approach to prosthetic replacement. AVre, however, is a technically demanding procedure. Analysis of mechanisms of valve dysfunction, precise measurement of leaflet and root geometry, and decisions regarding repair patch size, must be made intra-operatively while the heart is arrested and the aorta open. In experienced centers, however, the short and long-term results of AVre are excellent but the repair rate remains suboptimal due in great part to the trial and error method applied. The main goal of AVre is to repair the geometry of the valve leaflets using non-leaflet tissue (pericardium treated with gluteraldehyde) to generate valve closure during diastole. While experienced surgeons are able to do this intra-operatively, consistent results and widespread application of AVre has been limited due to the steep learning curve with the procedure. To address these impediments to the application of AVre more widely, we propose to utilize the recent advances in 3D ultrasound imaging combined with image processing and modeling techniques to develop a tool for pre-procedure analysis of aortic valve function, and for surgical planning. Ultimately, the goal is to have a tool that can be used in the operating room, utilizing intra-operative imaging for analysis and planning. We propose three Specific Aims: Aim 1. Develop methodology for defining valve geometry, including: segmentation, statistical geometric models, and computational meshes. Aim 2. Develop and validate patient-specific finite element- based simulation of aortic valve closure and of valve repair. Aim 3. Create an interface between clinicians and technical developments to enable the work-flow for aortic valve repair planning, including end-template. To accomplish these goals we will employ a partnership with expertise in 3D ultrasound image processing, model building, and clinical aortic valve repair. This partnership has unique access to clinical care, industrial engineering and modeling, and a long track record of collaboration.